How to import .bobj files in Blender?
A Bobj file sounds like it could be a Binary OBJ file, However i believe this is not a specific standard of file. 

Blender's Fluid simulator outputs bobj.gz as a format in binary, and compressed.

Edited:

bobj files are used in the fluid tab of the physics settings. 

Make sure the bobj.gz files are in a directory of their own, and then goto that directory in the highlighted field.
Make sure you only have the directory name in the field, and not the file name of the fluid cache.

You also need to make sure the file names do not change from fluidsurface_final_xxxx.bobj 
and set the viewport Display to Final.